Spark plug



M. EVANS SFARK PLUG i Filed Sept. 14, 1923 March 23 1926.

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MICHAEL EVANS, OF PLADELPI-HA,'ENNSYLVNIA.`

SPARK PLUG.

Application ledscptelmberl, 1923f Serial No. lll.4

My invention relates to 'i spark plugs for` i automotive engines and the like, and relates more particularly to an improved form of spark plug provided with a spark gap device for intensifyingthe ignition spark, and also provided with meansfcr permitting the observation, when desired, lof the operation of the spark plug, as well as the conditions within the cylinder dui-ing the operation of the engine.

It is well known to those skilled in the art that the intensity of the ignition spark will be greatly increased by the provision, in the ignition circuit, of anauxiliary spark gap, and it is also well known that faults in the operation of the engine, particularly in multi-cylinder engines, can often be ascertained and determined by the manner in which such auxiliary spark gaps are operating, as well as by the color of the exploding gases within the cylinder at the time of the ignition.

The principal objectfof my invent-ion is to provide, in a unitary structure, a simple and eliicient form of spark plug adapted to be mounted in the cylinder head of a gas engine or the like, havingincorporated therein a spark gap device for intensifying the during the time Vwhen it is not desired to observe the operations within the interior of the spark plug. Y

A further objectof my invention is to provide, in a device of the character aforesaid, certain improved details of construction.

The nature and characteristic features of my present invention will be more readily `understood fromthe following descriptiim` taken in connection ,with theaccompanying drawings forming part hereof, 'in which-l Figure l is a vertical, central, sectional view of a spark plugembodying the mainfeatures of my present invention;

Fie'. 2 is a frontelevation thereof;

Fig. 8 is ahorizontal section taken apv sumed lwhen it is not desired to observe the operations, that is to say, during the normal vfunctioning of the engine in connection with which the spark plug is used; and

Fig. 5 is an underneath plan view of the `lower end of` theV device,.illustrating a preferred arrangement of the sparking terminals. Y K

Referring to the drawings, in the particu .lar embodiment of my invention therein shown, 6. is the housing of the spark plug,

the lower tubular portion 7 of which is vthreaded' as at 8, `preferablywvith a nontapered thread, for a reason which will be hereinafter set forth.,` rihe threaded portion 8 engages the complemental threaded portion 9 of the cylinder head 10, and a lock nut 1l is also mounted on the threaded portion 8, a gasket l2 being provided be,-

.veen the lock nut ll andthe top surface of the cylinder head 10.'

Mounted in the housing 6 is an insulating member 13, preferably made of porcelain, oi' other suitable material, the insulating properties of which will not be deteriorated by the heat generated during the operation of the engine. The insulating.member 13 is provided, near its lower end, with a chamber 14e open at one side (seeFig. 1). The chamber lll is in communication with the interior of the tubular portion 7 through a passageway 55, which may be rformed by reducing the diameter of the lower portion of the insulating .member 13, as illustrated in Fig. l of the drawings.`

Mounted in the lower end ofthe insulating member 13 is a spark terminal device,

`which, iii the foi'in shown, comprisesA a threaded conducting rod l5, tlie'upper end of wbicn terminates within the chamber 14:o

Nuts 16 and 17 are mounted on the threaded rod 15 and serve to permit longitudinal adjustment of the upper end of said rod 15 within the chamber 111, for a purpose to be hereinafter set forth. The lower end of the spark terminal device comprises a bowshaped device 18, the sides 19 of which are arranged in proximity to, but not touching, the walls of the tubularportion 7 of the housing 6, being separated therefrom a suf iicient distance to permit the spark to jump to ignite the explosive mixture within the cylinder of the engine. Y

Mounted in the upper end of the insulating member 13 is a conducting rod 20, the lower end of which extends into the chamber 14 in proximity to the upper end of the rod 15 of the spark terminal device. The rod 2O is provided with an enlarged portion 21, forming a shoulder for the retention of the rod 2O inthe insulating member 13 at a fixed position. The upper end of the rod 2O is threaded, as at 21, and a nut 22 is mounted thereon for confining the rod in its proper position in the insulating member 1S, as above mentioned. 'A washer 23 may be disposed between the nut 22 and the upper end of the .insulating member 18, for the protection of the insulating member against breakage, serving also as a gasket to prevent leakage of the gasesfrom the interior of the cylinder.

F or the purpose of retaining the insulating member 13 within the housing 6, theup vper portion thereof may be reduced in diameter forming a. shoulder as at 24, a gasket 25 being interposed between said shoulder 2d and the interior shoulder 26 of the housing 6. A sleeve 27, made of insulating material, surrounds the portion of the insulating member 13 which extends above the top of the housing 6, and the lower end of the sleeve 27 bears against the upper end of the housing G. A threaded cap member 28 is mounted on the threaded portion 21 of the rod 20,

the upper end of the sleeve 27 being seatedv therein, so that when the cap member 28 is advanced sutiiciently upon the threaded portion 21 of the rod 2i), the insulating member 13 will be securely held in position within the housing 6. A knurled nut may also be mounted on the threaded portion 21 of the rod 20, for attaching the connecting wires of the ignition system of the automotive engine.

The housing 6 is provided with an oili`-set portion 30, arranged in alinement with the chamber 1d of the insulating member 13. Mounted in this ott-set portion 30 is al valve member 31, preferably spherical in shape, and having a central opening 32 extending therethrough. r)The spherical valve'member 31 is conlined at the proper location within the offsetvportion 30 'by means of a cylindrical threaded member 33 which. alsobas a and also serving to prevent leakage of central passageway 34., preferably of hexagonal or other non-circular interior contour, to facilitate the assembly and adjustment of the parts. A disc 35, made of glass or other transparent material, is mounted in theoif-set portion 30 in front of the opening 3/1 of the member a soft metallic washer or gasket 36 being preferably interposed between the inner' surface of the transparent disc member 35 and tne outer surface of the member this washer 36 serving to minimize breakage ofthe disc member 35, the gases from the interior of the structure. A threaded 'ring member 37 is mounted in the off-set portion 30 and serveslto confine the transparent disc member 35 in its proper position. The threaded ring member 37 may be provided with a screw driver slot 38, lfor the purpose of mounting and adjusting the same in the structure.

For the purpose of rota-ting the spherical member 31, the same may be provided i'n its upper portion with an aperture B9, preferably square in contour, which is engaged by the complementally shaped lower end 40 of a stem 41. The upper end of the stem 41 is provided with a handle`=12 for the manual operation of the same. The stem t1 is also provided with an enlarged portion 52, which is confined within an upwardly extending portion 13 of the off-set portion 30 by means of a threaded gland member 1141-, a suitable gasket or packing being interposed between the lower end of the gland 44 and the shoulder formed by the enlarged portion of the stem 11.

It will be noted, as hereinbefore set forth, that the lower end of the rod 20 is fixed in position within the chamber let, and that the upper end of the threaded rod 15 of the spark terminal device terminates within said chamber in proximity to, but not touching, the lower end of the rod 20, the nuts 16 and 17 being provided so that the opening between the ends of said respective rods may be adjusted the proper distance to form an auxiliary spark gap for the purpose of intensifying the ignition sparks which ump between the sides of the member 18, at the lower end of the spark terminal device, and the interior wall of the lower tubular portion 7 of the housing 6. It will, of course, be understood that whenever the spark plug is properly functioning, a spark will jump across the gap within the chamber 1-l Vwhenever an ignition spark umps at the terminal.

Ey reason of the passageway Awhich is afforded ythrough the opening 55, extending between the interior of the engine cylinder and the spark gap chamber 141-, when the compression in ther engine occurs, a certain amount of the explosive mixture will be forced into the chamber 14e, so that, in the event of the ignition spark ,not'properly jumping from the sides of' the terminal inember 18, the spark afforded at the auxiliary gap device will also serve to `ignite the explosive mixture, and by reason of the eX- plosive gases Ybeing contained within the chamber lll, the color of the same may be readily observed at the time of the ef-:plosion, for the purpose of indicating faults in explosions Within the engine cylinder, and

will also be protected against fouling through the deposit of carbon on the inner surface of the disc. Whemhowever, it is desired to observe the operations within the interior of the spark plug, the spherical valve member 3l is turned to the position shown in Figsl and 3 of the drawings, so that the action of the spark at the gap, between the ends of the roes 20 and l5, may be observedithrough the transparent Vwindow 35, as also the character of the explosion may be observed forthe purpose of indicating lack of compression in particular cylinders, and other faults in the operation of the engine. n

lt should be noted that, when the spherical valve member 31 is turned to the closed position, the pressure within the interior of the spark plug will tend to seat the same more firmly on the seat provided at the inner end of the member 33, and it should also be noted that, by the arrangement of the leek nntll on the threaded portion 8 of the tubular extension 7 of the housing hG, the

`spa-rk plug may be arranged'in the head of the cylinder' with the off-set portion 30 projecting in any desired direction for the purpose of affording a more convenient observation of the spark gap through the transparent member 35, which feature would not be obtained by the use of a tapered thread or a straight thread with a permanent shoulder, as in the ordinary spark plugs at present in common use.

It will be seen that there is thus provided a simple and eilieient form of spark plug, comprising a unitary structure in which there is provided an auxiliary spark gap device for intensifying the spai'k at the ignition points, said spark plug also having means for permitting the observation of the auxiliary spark gap as well as the conditions within the cylinders, which means are so constructed and arranged as to protect the observation window from strains and fouling during the normal operation of the engine, and said spark plug also having means for permitting the same to be mounted in the cylinder head with the observation window disposed in any desired direction.

Having thus described. the .ne-ture and characterisitc features of my invention, what l claim Letters Patent is: Y .n

l. A sparkplng comprisingia housing adapted to be mounted in the cylinder' of an automotive engine, conducting members, and means for insulating said conducting i i its) members from said housing, the structure y having an internal `spark gap chamber, in communication with the interior of `the engine cylinder, said conducting members having ends terminating in said chamber in proximity to each other to form an auxiliary spark gap therebetween, a tran, iarent window nieinber mounted in a por'l on `of said housing,'opposite said internal spark Ygap chamber, a'valve member enclosedly mounted in said housing and interposed be-` tween the window member and the spark gap chamber, adapted to be mounted in the cylinderof an automotive engine and externally extending manually operable means for rotating said valve member between the open and closed positions.

2. A spark plugcomprising a-housing adapted to be mounted in the cylinder of an automotive-engine, conducting members, and means for insulating said conducting members from said housing, the structure having an internal. spark gap, chamber in communication lwith the interior of the engine cylinder, said conducting members lhaving ends terminating in said chamber in proximity to each other to form an auxiliary spark gaptherebetween, said housing new and desirev tosecure by having an olf-set portion-in alinement with the spark gap chamber, a transparent-wini dow member mounted in said off-set portion, a valve member enclosedly mounted in said olf-set portion and interposed between the window member' and the spark gap chamber, and adapted to close the communication between said chan'iberand the inner surface of the window member and externally extending manually operable means 'for rotating said valve member between the open and closed positions.

8. A. spark .plug comprising a housing adapted to be mounted in the cylinder of an automatic engine, conducting members, and means for insulating said conductingmembers from said housing, the structure having an internal spark gap chamber' in communication with the interior of the engine cylinder, said conducting members having' ends terminating in said chamber in proximity to each other to form an. auxiliary spark gap therebetween, one of said conducting members being adjustable with respect to the other, said housing having an oif-setportion .in alinement with the spark gap chamber, a transparent window member mounted in said ot-set portion, va valve member enelosedly mounted in said ofi-set portion and interposed between the window member and the spark gap chamber, and adapted to elose the communication between said chamber and the inner surface of the window member and externally extending manually operable meanslfor rotating said valve member between the open and elosed positions. v

4. A spark plug comprising a housing adapted to be mounted in the eylinder of an automotive engine, a unitary insulating member mounted therein, said insulating member having an internal park gap chamber formed therein, said insulating member being so shaped as to ai'lord a eom munieation between the spark gap chamber and the interior ot the eylinder, eondueting members mounted in said insulating member having their ends terminating in said ehamber in proximity to eaeh other to form an auxiliary spark gap therebetween, a transparent window member mounted in a portion ot' said housing opposite said internal spark gap chamber, a valve member mounted in said housing interposed between the window member and the spark gap Chamber, and adapted to elose the Communication between said Chamber and the inner surface of the window member and externally extending manually operable means for rotating said valve member between the open and elosed posit-ions.

5. A spark plug Comprising a housing, adapted to be mounted in the eylinder of an automotive engine, a unitary insulating member mounted therein, said insulating member having an internal spark gap chamber formed therein, said insulating member being so shaped as to afford a eommuniea tion'between the spark gap chamber and the interior of the eylinder, Conducting 'members mounted in said insulating member having their ends terminating in said chamber in proximity to eaeh other to form an auxiliary spark gap therebetween, said housing having an off-set portion in alinement with the Chamber in the insulating member, a transparent window member mounted in said off-set portion, a valve member mounted in said olif-set portion and interposed between the window member and the spark gap chamber and 'adapted to elose the eommunieation betweenV said chamber and the inner surface of the window mem-V and means for insulating said eondueting members Yfrom said housing, the structure having an internal spark gap Chamber 1n Communication with the interior of the en` gine eylinder, said eondueting members hav ing ends terminating in said internal ehan1- ber in proximity to each other to form an auxiliary spark gap therebetween, said housing having an off-set portion in alinement with the spark gap chamber, a transparent window member mounted in said oli'- set portion, a spherical valve member enelosedly mounted in said oli-setA portion and interposed between the window member and trie spark gap Chamber, and externally extending manually operable means for rota-ting said Ya ve member between the open and elosed positions.

7. A spark plug Comprising a housing adapted to be mounted in the eylinder of 'an automotive engine, conducting members,

and means for insulating saideondueting members from said housing, the structure having an internal spark gap chamber in communication with the interior of vthe en` gine eylinder, said conducting members having ends terminating in said internal chamber in proxii'nity to eaeh other to 'form an auxiliary spark gap therebetween, lsaid housing having an Vott-set portion in alinement with the spark gap chamber, a spherieal valve member enelosedly mounted in said oit-set portion, a valve seating member threaded in said oit-set portion having an opening extending therethrough, a transparent window member mounted in said loft-set portion adjacent to said valve seating member, a ring member threaded in said off-set portion for retaining said window member, and manually operable means for rotating said valve member.

In testimony whereof, I have hereunto signed my name.

MICHAEL EVANS. 

